Photochromic film of 6-nitro-1′, 3′,3′-trimethylspiro-[2H-1-benzopyran -2, 2′-indoline] prepared by plasma polymerization

Polymeric film of 6-nitro-1′, 3′, 3′-trimethylspiro-[2H-1-benzopyran-2, 2′-indoline](SP) was prepared by a plasma polymerization process and showed good surface morphology. It was found by ultraviolet-visible and infrared absorption studies that the molecular structure of SP after polymerization revealed a structure almost identical to that of the original compound. The film showed reversible photoisomerization and, accordingly, photochromism. These photochromic properties were much better in the polymerized film than for film prepared by the evaporation process.